1. Field of the Invention
The present invention relates a pinhole video camera as a non-focus video camera.
2. Description of the Related Art
Generally, a pinhole video camera, which changes, without focusing, image of a subject in an range from a point closely adjacent to the camera to a point far from the camera into electrical signals, utilizes xc2xc-inch fixed charged coupled device.
However, in the above-mentioned conventional pinhole video camera, overall area of the charged coupled device can not effectively be utilized due to fisheye characteristics of a lens disposed between the fixed charged coupled device and the pinhole. As a result, with the conventional pinhole camera, it is impossible to take pictures because of low luminance, and there is a problem that it is impossible to adjust focus of a subject in an range from a point closely adjacent to the camera to a point far from the camera, resulting in unclear image.
The present invention has been made in consideration of the above-mentioned problems, and it is therefore an object of the present invention is to provide a pinhole camera in which a conical lens with an apical angle of 91.13xc2x0 to 91.15xc2x0 is used to correct the fisheye characteristics, and ⅓-inch fixed charged coupled device and a pinhole with a diameter of 0.8 mm are adopted to obtain clear image of a subject in an range from a point closely adjacent to the camera to a point far from the camera with strong contrast.
In order to accomplish the aforementioned objects, the pinhole video camera according to the present invention comprises: a printed circuit board to which ⅓-inch fixed coupled charged device is attached; a holder fixed so as to cover a front surface of the coupled charged device of the printed circuit board; a lens holder having a pinhole with a diameter of 0.8 mm; a conical convex lens with an apical angle of 91.13xc2x0 to 91.15xc2x0, the conical convex lens fixed on a rear face side of the pinhole of the lens holder.
In the above-mentioned pinhole video camera, the lens holder may be movable in relation to the holder in a direction of a thickness of the fixed coupled charged device.
Further, in the pinhole video camera described above, it is possible to provide a coaxial cable, and the coaxial cable comprises: a central conductor; a first cylindrical screened conductor disposed outside of the central conductor through an insulating body; a second cylindrical screened conductor disposed outside of the first cylindrical screened conductor through an insulating body; and an outer covering covering an outer periphery of the second screened conductor, wherein the first and second cylindrical screened conductors are used for supplying current to drive the pinhole video camera.
Still further, in the coaxial cable described above, the first and second cylindrical screened conductor may comprise aluminum foil and a metal knit conductor covering the aluminum foil.
Further, in the pinhole video camera according to the present invention may further comprise a connector for connecting the coaxial cable to the pinhole video camera, and the connector comprises a plug connected to an end of the coaxial cable and a plug receptacle fixed to the pinhole video camera, and the plug comprises: a pin-shaped central contact connected to the central conductor of the coaxial cable; a cylindrical outer contact disposed outside of the pin-shaped central contact in such a manner as to cover the pin-shaped central contact through an insulating body, the cylindrical outer contact being connected to the first cylindrical screened conductor of the coaxial cable; and a cylindrical housing disposed outside of the cylindrical outer contact in such a manner as to cover the cylindrical outer contact through an insulating body, and the cylindrical housing being connected to the second cylindrical screened conductor of the coaxial cable, the plug receptacle comprises: a cylindrical housing with a flange at an axially intermediate portion thereof on an outer periphery thereof, a portion of the cylindrical housing on a side opposite to a side that the plug is connected with the flange in between machined to be a screw, a nut engaged with the screw, the cylindrical housing inserted into and engaged with the cylindrical housing of the plug; a central contact formed on a central portion in the cylindrical housing, the central contact having an insertion portion of the pin-shaped central contact of the plug on a side thereof, the other side of the central contact projecting from one side of the cylindrical housing; a contact disposed so as to cover the central contact in the cylindrical housing through an insulating body, the contact connected to a cylindrical contact which is engaged with the cylindrical outer contact of the plug, the contact projecting from one side of the cylindrical housing; and a contact connected to the cylindrical housing through a conductor, the contact projecting in parallel with the central contact from one side of the cylindrical housing.